Description: Unicellular thalli ovate, ellipsoidal, or spherical. Protoplast is colorless and contains a leucoplast. Two isokont, anterior flagella. Pyrenoids absent but starch granules present in abundance. Stigma present or absent. Two to four contractile vacuoles inserted at the apex near the flagella. Cell wall present, occasionally exhibiting longitudinal striae. Cell wall may be covered with a fine gelatinous coat. A papillum may absent or present. Asexual reproduction by zoosporogenesis. Four to eight daughter cells produced. Sporangium retains parental flagella and motility during cell division. Division plane may be longitudinal or transverse. Aplanospores have been reported. Palmella, akinete, and amoeboid stages have also been reported. Sexual reproduction isogamous, anisogamous, or oogamous depending on the species. Gametes observed to possess cell wall. Fusion occurs through pairing at the apices with the formation of a protoplasmic bridge. Gamete walls ultimately lost, followed by the development of the zygote which often accumulates "haematochrome." Zygote germinates to produce four to eight products of reduction division. Cell wall in Polytomauvella of the type II lattice similiar to Brachiomonas, Chlorogonium, Chloromonas, Carteria and some species of Chlamydomonas.

Information contributed by: M. Buchheim.
The most recent alteration to this page was made on 7 Nov 2015 by M.D. Guiry.

Comments: Polytoma is often referred to as a "colorless Chlamydomonas" in that it resembles Chlamydomonas in many respects. Polytomauvella has been found in rain water pools that contain decaying vegetation. Many species are known largely or exclusively from culture. Polytoma has been collected world-wide. Lang undertook an ultrastructural study of P. obtusum and was the first to demonstrate the stellate structure of the flagellar transition region. Gaffal, Gaffal and Kreutzer, and Gaffal and Schneider have also examined P. papillatum at the ultrastructural level. Molecular data suggest an alliance with Chlamydomonas (Vernon-Kipp and Birky)

Numbers of names and species: There are 21 species names in the database at present, of which 19 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..

Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):

Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.

Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,
organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA)
and intended to be published in CD format.
These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above.
The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.